Infusion of drugs, medications, or other diagnostic and therapeutic agents into the vascular system of a patient is a task routinely required by modern medicine. Placement of central venous access devices is a common occurrence in hospitals for these purposes. They are essentially used to give intra venous medications, obtain venous samples of blood and obtain measurements of central venous pressure. Three of the most commonly used devices are the Totally Implantable Venous Access System (TIVAS), the Peripherally Inserted Central Catheter (PICC), and the Central Venous Catheter. A TIVAS usually consists of a reservoir compartment (the portal) that has a silicone bubble for needle insertion (the septum), with an attached plastic tube (the catheter). The device is surgically inserted under the skin in the upper chest or in the arm, and the catheter is inserted into a vein. A PICC is inserted in a peripheral vein, such as the cephalic vein, basilic vein, or brachial vein and then advanced through increasingly larger veins, toward the heart until the tip rests in the distal superior vena cava or cavo-atrial junction. The proximal end of the PICC remains outside of the body. A central venous catheter is also referred to as a chest catheter or a Hickman line. The distal end of the catheter enters the jugular vein and advances into the superior vena cava. The proximal end of the catheter tunnels under the skin and exits on the chest wall. When inserting a PICC or Hickman line, a stainless steel wire (guide wire) is used to guide the flexible catheter through the vasculature to its intended site of placement.
Angiography is a medical imaging technique in which an X-ray picture is taken to visualize the inner opening of blood filled structures, including arteries, veins and the heart chambers. A computed tomography (CT) technique can also be used to generate detailed three dimensional images. Because blood has the same radiodensity as the surrounding tissues, a radio-contrast agent is added to the blood to make angiography visualization possible. A large amount of contrast agent infused in a short period of time is usually necessary for successfully obtaining images with good contrast. Power injection equipment is routinely employed with central venous access catheters to achieve the required rate of delivery. Clinical injection rates can go as high as 5 mL/sec. Other medical procedures, such as in the treatment of dehydration and sepsis, may also require infusion of large amounts of fluid through a central venous line.
PICC insertion is less traumatic compared to a central venous catheter. Multiple-lumen catheters have the distinct advantage of enabling multiple diagnostic and therapeutic access through a single placement procedure. Some patients undergoing imaging examinations may already have a PICC placed for other purposes. Insertion of a traditional central venous catheter solely for the purpose of imaging examination can be traumatic for the patients and cumbersome for the medical staff.
Existing multiple-lumen PICCs may be used for power injection of diagnostic and therapeutic agents. The internal lumens of existing multiple-lumen PICC are generally configured as represented in FIGS. 1A and 1B. In the PICC depicted in FIG. 1A, the lumens 110 are formed by three septa 120 arranged radially, extending from the outer wall 130 of the catheter to the center of the catheter. Angular corners are formed at the intersection between the septa 120, and between each of the septum 120 and the outer wall 130 of the catheter. During the placement of a PICC, one of the lumens must be used to thread the guide wire. The angular corners in the catheter lumens have a tendency to catch the guide wire, and make PICC placement difficult. The radially arranged lumens 110 in FIG. 1A also do not perform well under pressure. The angular corners of the lumens are prone to rupture under pressure.
FIG. 1B depicts the cross section of another example of a multiple-lumen catheter having three lumens with circular cross sections. A larger lumen 140 is formed on one side of the catheter, with two smaller lumens 150 on the other side. The larger lumen 140, which lacks any angular corners, is naturally suited to be used with the guide wire for advancement of the PICC. However, the diameter of the larger lumen 140 is relatively small compared to the usable space within the body of the catheter. As can be seen when viewing the FIG. 1B embodiment, the use of space is not very efficient. The small diameter of the larger lumen 140 also restricts the maximum flow rate achievable through this lumen. High pressure resulting from the required flow rate for power injection would reach unsafe levels that may cause catheter rupture. Further, the structural weak point of the larger lumen is its outer wall 160. In the event of a catheter rupture, the outer wall 160 of the larger lumen 140 is the likely place to breach. Fluid in the larger lumen 140 may escape into the surrounding tissue, and cause complications. For the foregoing reasons, a PICC with the FIG. 1B configuration is generally not suitable for power injection.
To increase the pressure rating for the multiple-lumen PICCs with the afore-mentioned existing lumen configurations, a practitioner may have to increase the diameter of the inner lumen by increasing the overall diameter of the PICC. The multiple-lumen PICCs that are currently available on the market are generally of large diameters, typically 6 Fr or larger. The relatively large size of the existing multiple-lumen PICC is not an ideal solution, because it would make PICC placement more difficult and diminish the advantage of PICCs over central venous lines. Accordingly, it would be desirable to have a multiple-lumen PICC capable of use for power injection of diagnostic and therapeutic agents, while still having a traditional outer dimension and being configured (without small angular corners) for easy insertion over a guide wire. Particularly it would be desirable to have a triple lumen power injection PICC with an outer diameter of 5 Fr or less. Additionally, it would be desirable to have a multiple-lumen PICC that is fail safe. In case of a lumen rupture when the catheter is used under pressure, the integrity of the exterior wall is retained.